Page 2 of 3 FirstFirst 123 LastLast
Results 16 to 30 of 32
  1. #16
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

    Default

    At a guess taking wear into account they are probably 14 DP.

  2. #17
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Sorry, I did see but thought I'd check if we had a hob first.

    You're both correct, 14DP 14.5° PA

    Unfortunately we only have a 14DP 20° hob, our 14.5° range tops out at 15DP; the other half of the company that deals with larger gears has one in 14.5°, but it's much too big to fit our machines. They will be able to make them for you, but it will be at the normal shop rate, not the "after hours private job special"

  3. #18
    Join Date
    Jul 2020
    Location
    Canberra
    Posts
    15

    Default

    [QUOTE=elanjacobs;1971411]Sorry, I did see but thought I'd check if we had a hob first.

    You're both correct, 14DP 14.5° PA

    Unfortunately we only have a 14DP 20° hob, our 14.5° range tops out at 15DP; the other half of the company that deals with larger gears has one in 14.5°, but it's much too big to fit our machines. They will be able to make them for you, but it will be at the normal shop rate, not the "after hours private job special"[/QUOTE


    Hi elenjacobs,

    Many thanks for your efforts and reply. This may be sacrilegious to a gear make, but what would be the consequences in this application of meshing 14.5 and 20 degree pressure angle gears of the same pitch together? I have attached a marked up scanned photograph of the arrangement which shows gear no.1 and gear no.2 from my previous post are permanent fixtures and mesh with a 20 tooth idler tumbler gear which of course would be worn.

    From the stub shaft of gear no.2 to the lead screw various gears are arranged in accordance with the thread cutting guide chart to accommodate different threads per inch. I guess if the worst came to the worst, a new 20 tooth idler gear with 20 degree p.a. could be made?

    What do you think?

    Regards,
    Rob
    Attached Files Attached Files

  4. #19
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    You could completely convert to 20 degree pressure angle.

    Sent from my SM-G973F using Tapatalk

  5. #20
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    If those 3 gears don't have to mesh with anything else, converting to 20* would be the way to go. Mixing pressure angles is....not good; they feel "notchy" when rolled together and will run louder and wear much faster. It also requires extra clearance, so if the centres are all fixed the gears would need to be cut with a correction factor to allow (above my pay grade for the moment).

    It's like a space-saver spare wheel; it'll get you out of a bind if you have to, but don't go too fast and put the proper one back on ASAP.

  6. #21
    Join Date
    Jul 2020
    Location
    Canberra
    Posts
    15

    Default

    Quote Originally Posted by elanjacobs View Post
    If those 3 gears don't have to mesh with anything else, converting to 20* would be the way to go. Mixing pressure angles is....not good; they feel "notchy" when rolled together and will run louder and wear much faster. It also requires extra clearance, so if the centres are all fixed the gears would need to be cut with a correction factor to allow (above my pay grade for the moment).

    It's like a space-saver spare wheel; it'll get you out of a bind if you have to, but don't go too fast and put the proper one back on ASAP.
    Hi elanjacobs,
    Again many thanks for your help and advice. I now realise that I need the second 20 tooth tumbler gear to be able to reverse the direction of rotation of the gear train. I found a badly stripped one in amongst all the bits and pieces that came with the lathe.
    So in summary, if I stick to the 14.5 degree pressure angle I will now need three gears cut. You mentioned in an earlier post another branch of your firm which could cut the 14.5 degree gears. Would it be possible for you to get a quote to make the three gears if I send details of the additional 20 tooth tumbler gear tomorrow? I believe the original gears are cast iron, but replacements should be steel. Will leave the choice of grade up to you. Many thanks,
    robjean

  7. #22
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    There are several firms around the place that cut gears, but it will cost you $100's. Several of us cut gears and may be able to cut them for you if needed.

    Michael

  8. #23
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Quote Originally Posted by robjean View Post
    Hi elanjacobs,
    Again many thanks for your help and advice. I now realise that I need the second 20 tooth tumbler gear to be able to reverse the direction of rotation of the gear train. I found a badly stripped one in amongst all the bits and pieces that came with the lathe.
    So in summary, if I stick to the 14.5 degree pressure angle I will now need three gears cut. You mentioned in an earlier post another branch of your firm which could cut the 14.5 degree gears. Would it be possible for you to get a quote to make the three gears if I send details of the additional 20 tooth tumbler gear tomorrow? I believe the original gears are cast iron, but replacements should be steel. Will leave the choice of grade up to you. Many thanks,
    robjean
    Best if you contact them directly instead of back and forth through me https://www.hardmanbros.com.au/contact

  9. #24
    Join Date
    Feb 2013
    Location
    Laidley, SE Qld
    Posts
    1,038

    Default

    On US based machining fora Boston Gear is often mentioned as an answer to someone's broken/missing change gear problem.

  10. #25
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    Ronson gear in Melbourne also carry a good range of stock gears made by KHK who's catalog is publicly available. Prices are pretty good.

    Sent from my SM-G973F using Tapatalk

  11. #26
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    I had a look at the KHK site via Ronson at the beginning and they don't seem to have 14DP (unless I missed it); apparently it's a bit of an oddball size, it usually jumps from 12 to 16 DP

  12. #27
    Join Date
    Aug 2008
    Location
    near Rockhampton
    Posts
    6,216

    Default

    Quote Originally Posted by elanjacobs View Post
    Best if you contact them directly instead of back and forth through me https://www.hardmanbros.com.au/contact
    Ahh you work for them. Here is one of their gears.

    I hit a few too many rocks in the slasher. It still goes round and round.

    20200613_171510.jpg


    As for the lathe change gears. I would make them out of cast iron. Easier to machine then steel. Someone with a CNC mill with a CNC dividing head and gearotic could do it pretty easily, even a metric transposing gear.

    There is always a gear cutting set. https://www.ebay.com.au/itm/8-Pcs-In...8/293622567298
    Gold, the colour of choice for the discerning person.

  13. #28
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    I work for R&I, Hardman's bought us a while back, but it's all in the same place. They do the big stuff, we do the (really) small stuff; we have hobs going all the way down to 0.1 Mod

  14. #29
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Quote Originally Posted by bob ward View Post
    On US based machining fora Boston Gear is often mentioned as an answer to someone's broken/missing change gear problem.
    Just had a look through their catalogue... 12 and 16 DP, no 14

  15. #30
    Join Date
    Jul 2016
    Location
    Melbourne
    Age
    35
    Posts
    1,522

    Default

    I have also had gear cutting and manufacturing in seaford hob me 14DP gears before at reasonable cost.

    Sent from my SM-G973F using Tapatalk

Page 2 of 3 FirstFirst 123 LastLast

Similar Threads

  1. Mars lathe
    By Ueee in forum EBAY, GUMTREE, and other off forum sales sites
    Replies: 8
    Last Post: 15th Mar 2017, 09:06 PM
  2. Mercury Nova Mini Lathe
    By B the B in forum METALWORK GENERAL
    Replies: 7
    Last Post: 22nd Mar 2015, 11:41 PM
  3. Mars bar no, Mars lathe!
    By neksmerj in forum METALWORK GENERAL
    Replies: 20
    Last Post: 29th Sep 2012, 08:18 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •